1. Field of the Invention
The present invention relates to a porous refractory inorganic oxide product and a process for producing the same. More particularly, it relates to a porous refractory inorganic oxide product having excellent mechanical strength and large specific surface area and relatively middle pores (referred to as mesopores) which is suitable for a support of catalyst and a catalyst and a process for producing the same.
2. Description of the Prior Art
The inorganic oxides such as alumina, silica, titania, zirconia, thoria, boria, crystalline aluminosilicate and crystalline and amorphous natural minerals have various usages such as an adsorbent, a catalyst and a support of catalyst. One of the most important characteristics required for an adsorbent, a catalyst and a support of catalyst is a range and capacity of a pore distribution. Excellent result is given for the purpose of the refractory inorganic oxide depending upon the characteristic.
In the measurement of a pore distribution of a porous refractory inorganic oxide product, various pore distributions can be provided depending upon an inorganic oxide, a source thereof, and a condition for preparation such as a preparation of a product and a firing temperature. Thus, the pores are mainly affected depending upon primary and secondary grains in the particles of the inorganic oxide for the product. Thus, the pore distribution may be controlled in certain degree by a control of the process, though the pore distribution of the resulting product is mainly depending upon the kind of the inorganic oxide for the product.
Various processes and operations for controlling pore distribution such as a selection of a source, a use of a suitable additive and an improvement of a shaping process have been proposed, because the control of pores is quite important for imparting remarkably superior characteristic for a specific purpose in the use of the product as a support of catalyst and a catalyst. Thus, the control of pores must be attained without losing physical properties such as a mechanical strength and a wearing durability.
The pore sizes of the porous refractory inorganic oxide product are classified into three groups of fine pores having a radius of less than 100 .ANG. (micropores) middle pores having a radius of 100 .ANG.-1000 .ANG. (mesopores) and large pores having a radius of more than 1000 .ANG. (macropores). Certain reactions in which the presence of mesopores is important, have been known. For example, the diffusion in pores is accelerated to advantageously perform reactions in the presence of the mesopores. On the other hand, it has been difficult to provide intentionally as desired such mesopores at high capacity by the conventional technology. Alumina has various usages as catalysts and supports of catalyst. It has been desired to obtain a product having a high content of mesopores in concentration, together with micropores but it has been difficult. In accordance with the present invention, the requirement has been attained. Thus, it is remarkably advantageous in chemical industries, to produce a porous refractory inorganic oxide product having mesopores having said characteristics at high ratio regardless of a kind of the inorganic oxide used with a relatively economical source, an additive and an easy mechanical process.
From the aforementioned viewpoint, the inventors have studied to obtain a porous refractory inorganic oxide product having the excellent aforementioned characteristics without losing physical characteristics such as a mechanical strength and a wearing resistance.